Lambda(1405) as a multiquark state

Abstract

In the QCD sum rule approach we predict the $\Lambda$ (1405) mass by choosing the ${\pi }^0{\Sigma }^0$ multiquark interpolating field. It is found that the mass is about 1.419 GeV from ${\Pi }_1(q^2)$ sum rule which is more reliable than ${\Pi }_q(q^2)$ sum rule, where ${\Pi }_q(q^2)$ and ${\Pi }_1(q^2)$ are two invariant functions of the correlator $\Pi (q^2)$. We also present the sum rules for the $K^{+}p$ and the ${\pi }^{+}{\Sigma }^{+}$ multiquark states, and compare to those for the ${\pi }^0{\Sigma }^0$ multiquark state. The mass of the $\Lambda$ (1600) can be also reproduced in our approach.

Comments: revtex, 12 pages, 13 ps figures; considerable revision, accepted in Eur. Phys. J. (A)